Pyrolysis of Pentoses

Tanaka Yoshiyasu, Nakamura Tadashi

doi:10.1246/nikkashi.1975.705

The pyrolysis of pentoses was carried out at 190-300° C by using DTA and TG.<BR>DTA curve consisted of three peaks: the first, endothermic melting point, the second, endothermic decomposition and the third, exothermic peak beginning at about 300° C. The beginning of decomposition of pentoses occurred at 194° C. Differences between the decomposition temperatures and the melting points of pentoses were 100° C for ribose, 60° C for lyxose, 50° C for xylose, and 40° C for arabinose.<BR>The weight loss curve obtained by TG showed two types: the one, for D-arabinose and D-ribose and the other, for D-xylose and D-lyxose. TG curves showed two steps of weight loss at 240° C.<BR>Ten ml aqueous solution was prepared from pyrolysis product of 30.0 mg pentose for each 10° C rise in temperature between 190° C and 300° C. The aqueous solution of pyrolysis (250° C)products of D-xylose showed the lowest value of transmittance at 520 nm. The solutions of pyrolysis (270° C) products of D-lyxose, D-ribose, and D-arabinose showed the lowest value at 52O nm. This showed the decomposition of pentoses was completed at these temperatures. The solutions, treated with Schales reagent showed the transmittance at 420 nm. which relates with the reducing power of them. The aqueous solutions of pyrolysis (220° C) products of pentoses showed the highest transmittance. The transmittance of these solutions markedly decreased at 220-230° C (from 90% to 30% for D-xylose). The solutions in which pentose could be detected contained finally 1.48% D-xylose, O.94% D-ribose, 1.40% D-arabinose and O.71% D-lyxose in the solution of pyrolysis (230° C), (240° C), (240° C) and (240° C) products, respectively.

Pyrolysis of Pentoses

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